Size
wingspan about 33 mm, based on three Internet photos
larva length to 28 mm
Identification
Adult: forewing white with thick black or dark gray lines and one or more dark-scaled veins; AM and PM lines scalloped; discal spot dark, usually surrounded by dark lines; terminal line a series of dark spots; hindwing similar but discal spot not surrounded by dark lines, and veins not dark-scaled
Larva: head green with ten prominent black spots; body yellowish-green dorsally with faint green middorsal stripe; subdorsal stripe white, edged on either side with fine dark green line; supraspiracular area green with pair of wavy broken dark lines; spiracular stripe yellow
[adapted from description by Canadian Forest Service]
Range
southern British Columbia to California
Habitat
coniferous forests; adults are nocturnal and come to light
Season
adults fly in September and October
larvae from May to August
Food
larvae feed mainly on foliage of Western Hemlock and Douglas-fir; other hosts include Grand Fir, Amabilis Fir, Sitka Spruce, Western Redcedar
Life Cycle
one generation per year; overwinters as an egg; larvae feed from May to August; pupation occurs on foliage in August; adults emerge in September and October and lay up to 115 eggs singly or in small groups on undersides of needles
[adapted from text at Canadian Forest Service]
See Also
False Hemlock Looper (
Nepytia canosaria) does not occur west of the Rockies, its forewing lacks black-scaled veins, and even pale specimens have some amount of dark speckling scattered across the wing
other Nepytia species have grayer wings
Internet References
pinned adult image plus description, distribution, flight season, foodplants (Jeff Miller, Macromoths of Northwest Forests and Woodlands; USGS)
live larva images plus description, foodplants, biology, feeding damage (Canadian Forest Service)
collection dates and locations of 5 specimens in California (U. of California at Berkeley)
distribution in Canada British Columbia only (CBIF)